Water-cooled furnace door frame



g 13, 1940- E. .1. MoDONNELL I 2,211,544

WATER-COOLED FURNACE DOOR FRAME Filed May 26, 1939 INVENTOR Edward J McDonnell Patented Aug. 13, 1940 UNITED STATES WATER-COOLED FURNACE DOOR FRAME Edward J. McDonnell, Fox Chapel, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jers Application May 26,

3 Claims.

This invention relates to a furnace door frame of the type commonly used on metallurgical furnaces as for example, open hearth furnaces where the temperatures within the furnaces are exceedingly high and where water is used for the protection of the door frame, and is for a door frame having an improved arrangement for circulating the water therethrough in such manner as to afford a greater amount of protection to the door frame than has been secured by constructions heretofore provided and wherein the door is less susceptible to injury by reason of the accumulation of deposits of sediment and foreign material or to attack by chemicals which maybe in the water.

Specifically, the invention is for an improvement on furnace door frames of the type shown in the patent to W. P. Chandler No. 2,084,017 dated June 15, 1937. Furnace door frames of this type comprise a hollow structure having an upper body portion having depending legs, the legs and body portion defining an arched door opening. lhis structure is mounted on the exterior of the furnace so that the greater portion of its area is separated from the direct heat of the furnace by the intervening refractory walls of the furnace, but the portion of the frame forming the boundary of the arched doorway is exposed to the direct heat of the furnace and is therefore most susceptible to destruction if it is not properly cooled. As shown in the said Chandler patent, it has heretofore been proposed to form in that part of the structure which defines the arched doorway, a duct separate from the remainder of the interior of the hollow body into which the water may be first circulated before it is discharged into the hollow structure generally so that the water when it is coldest first contacts the part of the frame which is most susceptible to destruction. This duct as shown in the Chandler patent may be formed from a section of tube welded between the sheet metal plates forming the body and legs of the structure.

According to the present invention there is provided a door frame of the general type described having a body portion and leg portions and having a separate duct built into that portion which defines the arch or doorway. In the present invention means is provided for introducing the cooling water into one end of this duct, the arrangement being such that substantially all of the water so introduced has to traverse the entire length of the duct after which it is discharged into the hollow body of the door frame and carried away through a discharge outlet. This ar- 1939, Serial No. 275,907

the water have less opportunity, because of the I velocity of the stream, to attack or corrode the metal. The structure is furthermore so arranged that sedimentation for the most part will take place in the bottoms of the legs of the structure at a point where the door frame is protected from the direct furnace heat by the intervening furnace wall and where it cannot impede or deflect the circulation of the water through the structure and at a point where it can be conveniently cleaned out. The invention thus distinguishes from arrangements heretofore used as shown, for example, in the Chandler patent, where the cooling water is introduced into the circulating duct forming the margin of the door opening at a mid-point in the length of the duct so that the flow of water is divided, some of the water flowng toward each end. The mean velocity of the water by reason of such devision is reduced. Sedimentation in the structures referred to may accumulate adjacent the outlets of the duct, and accumulation adjacent one end of the duct restricts the flow of water through the branch of the duct so restricted further slowing down the velocity of the water in one or both sides of the duct so that the cooling of the unprotected part of the door is less efficient and the hazard of corrosion increased;

My invention may be more fully understood by reference to the accompanying drawing in which Figure 1 is a front elevation of a furnace door frame embodying my invention, part of the view being shown in section;

Figure 2 is a transverse vertical section through a door frame embodying my invention, along the plane of line 11-11 of Fig. 1, showing the frame in position at the front of a furnace structure;

Figure 3 is a transverse horizontal section in the plane of line III-III of Figure 1;

Figure 4 is a transverse horizontal section through one of the legs in the plane of line IVIV of Figure 1.

In the drawing the door frame comprises an upper body portion 2 having depending legs 3, the body portion and legs definlnga door opening 4. The structure is hollow, being preferably formed from sheet metal, the interior chamber in the upper portion of the frame being designated 2a and the hollow space within the legs being designated 3a.

Formed into the structure in that portion thereof which defines the arch or margin of the doorway is a means forming a continuous duct from the base of one leg over the top of the arch and down to the base of the other leg. This means may conveniently be formed from a tube, designated 5, built into the frame structure. The diameter of the tube is equal to the thickness of the frame as a whole as best shown, for example, in Figure 2, but its diameter is less than the full width of the legs 3 as best shown, for example, in Figure 4.

At the top of the frame is a pipe connection 8 to which a source of cooling water, not shown, may be connected. Leading from the connector 6 downwardly through the interior of the structure to the base of one leg is a water inlet pipe I, this pipe opening at 8 into one end of the duct or conduit 5.

Leading from the opposite end of the duct or conduit 5 at the point designated 9 is a cooling water discharge pipe II] which extends upwardly through the opposite leg from the pipe 7 and which has its upper end bent inwardly to a point near the center of the chamber 2a. Also secured to the top of the door frame is a second pipe connection II to which a water discharge pipe, not shown, may be connected. It is desirable but not necessary that an offtake pipe I2 extend through the interior of the frame structure from the pipe connection H to a point near the mid-plane of the frame structure.

In the bottom of each leg at the end of the duct 5 there may be provided a removable cleanout plug 13. These plugs give access to the interior of the duct or conduit 5. In addition removable clean-out plugs M are preferably provided at the bottom of each leg to give access to the space 3a inside each leg.

As shown in Figure 2, the frame structure is mounted on the front of the furnace structure A so that most of the area of the frame structure is protected from the direct heat of the furnace by the refractory walls of the furnace structure. This is true of the legs of the frame as well as the top, and only the marginal portion of the doorway formed by the duct 5 is exposed to the direct heat of the furnace.

With the present invention, water supplied to the connection 6 flows down the pipe 1, enters one end of the conduit 5 at the bottom of one leg, traverses the complete length of the conduit, flows at point 9 from the conduit or duct 5 into the pipe [0, and from this pipe discharges into the chamber within the frame structure filling the legs of the chamber with water and filling the top of the structure with water. After the interior of the chamber is full of water, the water discharges through the pipe l2 and the connection l l. Under some conditions the duct or conduit 5 may be provided with a very small vent hole 5a at the middle of the top of the arched portion thereof, this vent opening into the chamber 2a. This vent allows any steam which may be generated in the duct 5 to escape and also prevents any air from being trapped in the duct. While a very small volume of water may always escape through this vent, the main volume of the flow will be through the entire length of the duct or conduit 5. Since substantially all of the water which is supplied for cooling flows through the duct 5 in one direction, there is a relatively high velocity of water, this velocity being much greater than where the Water is introduced at the center of the duct and flows in opposite directions toward both ends. Because of the higher velocity of the water, its corrosive effect is reduced and its cooling effect is increased. By reason of the higher velocity of the water, any tendency toward sedimentation or the forming of incrustations is retarded with the result that the duct remains free of accumulated foreign substances for a considerable length of time and destruction of this part of the frame is very materially retarded. Any sedimentation that tends to occur occurs in the bottom portions of the legs to the outside of the duct 5. There is no forced circulation of water in these parts of the legs so that sediment may readily accumulate at these points. Being to the side of the duct 5 and thus protected from exposure to the direct heat of the furnace, sedimentation may occur in these parts of the legs Without danger of overheating or injury to the frame, and sediment can be removed from time to time through the removal of the clean-out plugs l4. While no means is provided for directing any forced circulation of fluid through the legs 3, water of course is always available to fill them and natural convective currents are set up. Furthermore, water in the space in the legs outside the duct 5 is cooled in the one case through the incoming 0 water which cools the pipe 1, the pipe I in turn cooling the surrounding body of water, and by the water contacting with some of the walls of the duct 5 and in the case of the other leg, water in the space 3a is cooled by the fact that Water discharging from the conduit or duct 5 flows through the pipe If! at high velocity and thus may carry heat from the water in which the pipe i0 is immersed, and this water is further cooled by contact with the portion of the duct 5. Excessive heating in the quiet zones of either of the legs is thus effectively prevented.

An important advantage of the pipe 58 is that if sedimentation occurs in the bottom of the leg in which the pipe i0 is located, this sedimentation can in no way interfere with or restrict the flow of water from the discharge end of the duct 5, as might be the case if the pipe Hi were not provided and the end of the duct 5 opened directly into the bottom of one of the legs. In the construction shown there is no likelihood of any incrustation or sedimentation occurring to restrict the free discharge of fluid from the liner end of the pipe Hi. The invention is thus intended to overcome many of the diiiiculties inherent in water-cooled door frames as heretofore designed and used without any appreciable increase in the cost of the door frame.

While the connection 6 has been designated an inlet connection and the connection H designated a discharge connection, it is apparent that the direction of flow could be reversed, although such arrangement would be less desirable by reason of the fact that the advantage of supplying the coldest water to the hottest part of the structure first would be lost.

While I have illustrated and described in detail one embodiment of my invention, it will be understood that various changes and modifications may be made therein within the contemplah tion of my invention and within the scope of the following claims.

I claim as my invention:

1. A water-cooled furnace door frame comprising a hollow metal structure having an upper body part and spaced depending hollow leg portions defining a doorway, means in said structure around the doorway forming a separate duct extending from the bottom of one leg across the top of the doorway and to the bottom of the other leg, and a water pipe connection leading into one end of the ductfrom the exterior of the structure, the other end of the duct opening into the hollow interior of the structure, whereby water may first flow through the duct and then fill the legs and upper part of the entire hollow metal structure.

2. A water-cooled furnace door frame comprising a hollow metal structure having an upper body part and spaced depending leg portions defining a doorway, means in said structure around the doorway forming a separate duct extending from the bottom of one leg across the top of the doorway and to the bottom of the other leg, a water pipe connection leading into one end of the duct from the exterior of the structure, the other end of the duct opening into the hollow interior of the structure, there being a pipe leading from said other end of the duct into the hollow interior of the structure above the lower end of the leg whereby the free end of said pipe is above the zone of normal sediment accumulation at the bottom of the leg.

3. A water-cooled furnace door frame compris ing a hollow metal structure having an upper body part and spaced depending leg portions, the structure defining an arched doorway, means in said structure immediately around the doorway forming a separate duct extending from the bottom of one leg to the bottom of the other leg, a water pipe connection at the top of said frame leading through the hollow interior thereof to the bottom of one leg and opening into one end of said duct, a pipe leading from the other end of the duct upwardly through the other leg and terminating in the interior of the top part, and a second pipe connection in the top of the frame opening into the hollow interior of the structure.

EDWARD J. McDONNELL. 

